ISRO's Chandrayaan 2: The forthcoming 48th day of the mission entails the most complex event when the Powered Descent of Lander is scheduled.
By Milind Kulshreshtha
ISRO’s Moon landing: Chandrayaan-2 mission commenced on July 22nd, 2019 with the lift-off from Sriharikota and has since successfully completed more than 44 days of Space flight. Crucial phases viz. Trans Lunar Injection, Lunar Transfer Trajectory, Lunar Orbit Insertion, Lunar Bound Phase and Lander Orbiter Separation have all been completed with clockwork precision by ISRO. But the forthcoming 48th day of the mission entails the most complex event when the Powered Descent of Lander is scheduled. This phase culminates in the soft touch down of the Lander on the Moon’s South Pole on Sept 7th, 2019 and release of a Rover on the Lunar surface. Both these activities are significant in India’s ambitious Chandrayaan Lunar Programme which commenced in 2008 with Chandrayaan-1 demonstrating India’s capability to leap from Low Earth Orbit (LEO) to a Lunar orbit for Moon rendezvous.
Vikram Lander Soft Touch down: As per latest ISRO updates, Orbiter and Lander (with Rover unit) have completed the scheduled de-orbiting maneuver on Sept 3, 2019, and are now independently orbiting Moon. The Orbiter unit shall continue to maintain its trajectory around the moon, whereas Lander orbit is gradually narrowing towards the Moon to affect the Powered Descent on Lunar surface. The 1,471Kg Lander is expected to have a touchdown descent velocity of 2 metres per second and is being guided to land on South Pole at 70.9°S, 22.7°E Moon coordinates. However, an alternative site at 67.7°S, 18.4° W too has been earmarked by ISRO for landing, if need arises.
The Lander is fitted with three payloads and one passive experiment to study the following on Lunar surface:-
(a) Lunar Seismic activity and measure Lunar quakes
(b) Lunar ionosphere which is a dynamic plasma environment
(c) Lunar surface temperature gradient and thermal conductivity (using probe inserted up to 10cm into the Lunar bedrock)
(d) Lunar laser ranging passive experiment using Laser Retro-reflector Array
Pragyan Rover with AI: On Sept 7th, 2019, after the scheduled Lander touch down and completion of various essential system checks, a side cover of Lander opens outwards to form a ramp to the Lunar surface on which the Rover shall roll down. Once on the Lunar surface, Rover’s solar panel unfolds for power generation. A fully powered on Rover consumes about 50W power, which is only half of power consumed by a domestic 100W incandescent lamp. Pragyan is a 27 kg six-wheeled ground traversing robotic Rover designed to move at 01cm per second. It has been ‘Artificial Intelligence’ (AI) trained earlier on Earth surface for obstacle avoidance etc. so as to improve its survival chances on the unknown Lunar South Pole. The Rover can move up to 500 m from the Lander position and is designed to communicate with the Lander unit during its exploration on the Lunar Surface while undertaking following scientific experiments:-
(a) Detection of Elements like Sodium, Mg, Ca, Ti, Fe and other trace elements (like Strontium, Yttrium, and Zirconium) using Alpha particle X-ray spectrometer
(b) Radiation analysis study for decaying plasma characteristics using its onboard Laser-induced Breakdown Spectrometer
The Scientific community eagerly awaits the Lunar data beamed back to Earth as part of Chandrayaan-2 Mission. For the next one year, the Orbiter shall continue in the Lunar orbit to send data related to Moon (e.g. Terrain Maps, ionosphere details, mineralogy, etc.) and other Celestial activities like Solar X-ray. However, the Lander and Rover have a life span designed for only one Moon day (equivalent to about 14 Earth days). On the expiry of their useful life, Orbiter is destined to crash into the Moon to disintegrate but the Lander and Rover shall become cold edifices on the South Pole itself. In the future, these inert Lander and Rover body frames shall be exposed to various vagaries of Lunar environment and, therefore, can make for interesting sample pieces for studying the effects of exposure on man-made structures at the Moon’s south pole.
In today’s Space Age, recent re-kindling of interest in the Moon (by USA, Russia, Japan, the European Space Agency, Israel and China) after last manned mission of Apollo 17 in 1972, is for more than a mere show of technical prowess for one-up-manship, as was seen during the Cold War era. Today’s Space activities have an underlying commercial demeanour, driven by the fact that Space-based systems (like GPS, Communication etc.) have become an integral part of daily human activities on Earth for billions of people and Moon holds the key for further scientific advancements, including Space sojourns of the future. This aspect has motivated huge investment in the Space sector by private players too (like SpaceX, Boeing, Blue Origin, etc.).
Similar to Apollo series, ISRO is assured to capitalize on the rocket and Space technology advances to experiment with human or humanoid spaceflights, first limited to the Low Earth Orbits and finally to the Moon itself. Today, new generation players in the Space race are creating an innovative infrastructure to achieve Space supremacy. The reasons for visiting the Moon and other Celestial bodies could be scientific or for a commercial benefit, but either way, such endeavours contribute towards a nation’s character. ISRO’s continued effort to focus towards Space research advances at a rapid pace shall ensure India’s presence in the Space frontier along with other advanced nations in time to come.
(Author is Artificial Intelligence and C4I expert. Views expressed are personal.)